Configure Debezium snapshot modes and incremental snapshots for large Postgres tables

Steps

1. Choose a snapshot.mode: initial performs a full table scan on first startup and then switches to streaming; never skips the snapshot; exported or initial_only are useful for one-shot migrations.
2. For large tables where a full initial snapshot would take too long or lock rows, use the incremental snapshot feature introduced in Debezium 1.6+: send a signal to the signaling table or Kafka topic to start an ad-hoc incremental snapshot of specific tables.
3. Incremental snapshots use a watermarking algorithm that interleaves snapshot chunks with the ongoing binlog/WAL stream, so no table lock is held beyond the chunk read.
4. Configure snapshot.fetch.size and the chunk size signal parameter to control memory pressure; smaller chunks reduce memory but increase the number of round trips.
5. Monitor the Debezium metrics (snapshot rows scanned, remaining tables) exposed via JMX or the metrics endpoint to track progress.
6. After the incremental snapshot completes, the connector continues streaming changes from the WAL without interruption.